Outlet-valve for air-compressors.



No. 6'8I,92I. Patented Sept. 3, |90I. J. S. LEWIS.

DUTLE'T VALVE FR AIR'COMPBESSOBS.

(Application led Nov. 17. 19mm (N0 Model-1 2 sheetssheet 1.

N0. 68|,92|. Patented Sept. 3, |90I. J. S.'LEWIS.

OUTLET VALVE FDR AIR COMPRESSORS.'

(Application led Nov. 17. 1900A (No Model.) 2 Sheets-Sheet 2.

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NI'TED STATES PAT-EN OFFICE.

JOHN S. LEWIS, OF YOUNGSTOWN, OHIO, ASSIGNOR TO WILLIAM TOD da COMPANY, OFv SAME PLACE.

OUTLET-VALVE FOR AIR-COM PRESSORS.

SPECIFICATION forming part of Letters Patent No. 681,921, dated September 3, 1901.

Application filed November 17, 1900. Serial No. 36.856. (No model.)

form of outlet-valve therefor which shall be positively closed by a moving part of the valve-gear, but disconnected therefrom, and which shall be opened by the excess of pressure in the cylinder over that in the outlet or delivery pipe.

My invention also comprises improved means for cushioning the outlet-valve during its opening movement; and it also consists in certain combinations and arrangement of parts, all as hereinafter more fully described and claimed.

In the accompanying drawings, which form part of this specification, Figure 1 is a sectional view of a portion of one head of an aircompressor, showing my improved outletvalve therein; Fig. 2, a horizontal section taken on the line @c w of Fig. 1; Fig. 3, a sectional View showing a modied construction of the plunger or guide, and Fig. 4 a sectional view showing another modification.

Referring to Fig. 1, the outer head 4 of the air-compressor is provided with an opening 5, which is in line with the opening 6 inthe valve-seat 7. The valve-seat is secured in the inner head of the air-compressing cylinder 8, and the space 9 between the inner and outer heads communicates with the outlet or delivery pipe of the air-compressor. I have illustrated only so much of the cylinder-heads of one end of the compressor as is necessary to show the connection of the outlet-valve thereto; but there may be two or more such valves located in each end of the air-compressor. In the opening 5 is secured the casing 10, having an outer extension forming guides 11, in which the sliding head 12 of the valve-stem 13 is adapted to move. The casing 10 is provided with a flange 15, extending around the opening 5, and also has an inner extension forming a cylinder 14, to which is secured the stationary piston 16. There is an opening through the center of the stationary piston forming a continuation of the cylinder 14, and in this cylindrical recess the guide 17 is adapted to reciprocate. This guide is preferably made in the form of a plunger, as shown in Fig. 1, with grooves 18 running the full length of its periphery, and a head 19 is secured to its inner end. The outer end of cylinder 14 is closed by a wall or head 20, in which the stuiiing-box 21 is located and through which passes the stem 13, which connects the guide or plunger 17 with the sliding head 12. It will be noted that the head 19, secured to the guide or plunger 17, is of less diameter thanthe cylinder 14, and the grooves 18 provide a continuously-open communication for the passage of air from the cylindrical recess 14 above the plunger to the space below the stationary piston 16. In Fig.

2 I have shown four such grooves; but a different number may be employed,if desired. The outlet-valve 23 is made of pressed steel of cupshaped form, and its cylindrical part 24 is adapted to slide on the stationary piston 16. Small openings 25 are provided in the walls 24 of the valve, so that the air beneath the stationary piston will be in communication with the outlet-passage 9 when the valve is forced to its seat by the head 19 of the plunger; but as the valve opens and the openings 25 are closed by moving over the stationary piston 16 the valve will then cushion on the air remaining between the valve and stationary piston 16 and also in the cylinder 14 above the plunger, since there is free communication through the grooves 18. The

rock-shaft 26 is secured in. any convenient manner to the head of the air-compressor and is provided with crank-arms 27, composed of two members, one on each side of the guides 11, these being connected by the pin 28,which passes through an opening 29 in the sliding head 12 and has a sliding bearing therein.

In Fig. 3 I have shown a modified construction in which the guide or plunger 17 does not extend beyond the cylindrical recess 14, but is provided with a stem 22, which is connected to and carries the head 19. Communication between the spaces above and below the guide or plunger may be established by means of grooves 18, as shown in Fig. 1,

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or by holes or passages 30 through the plunger, as shown in Fig. 3.

The operation of my device is as follows: As the rock-shaft and crank turn to move the head 12 and stem 13 outward the plunger 17 and head 19 are withdrawn into the cylindrical recess 14 of the stationary piston 16. The main compressing-piston (not shown) is at this time approaching this end of the main cylinder, and the outlet-valve 23 will remain closed u util the pressure within the main cylinder exceeds that in the outlet or discharge passage 9, as this is the pressure which acts through the openings 25 on the back of the valve 23 beneath the stationary piston 16. The plunger 17 acts merely as a guide for the head 19 and is adapted to reciprocate freely at all times in the cylinder 14, as the air-spaces above and below the plunger are in constant open communication with each other through the grooves or holes in the plunger. When the pressure in the main cylinder exceeds that in the outlet-passage, the head 19 having previously been withdrawn into the recess 14, the valve 23 will open freely, the cylindrical part 24 sliding on the stationary piston 1G until the openings 25 are closed. Then its movement will be checked and it will cushion on the air which lls the space in the valve below the stationary piston and the space in the cylinder 14 above and below the plunger. This constitutes the clearance-space, and as it is desirable that this should be as small as possible within certain limits the construction shown in Fig. 1 is peferred to that shown in Fig. 3, where the clearance-space is greater by the additional air-space surrounding the stem 22. When the compressor rst starts and there is very little pressure in the outletpassage 9, the outlet-valve 23 will open earlier and will not move with much force; but after the normal running-pressure is' attained in the outlet-passage the outlet-valve 23 will not open until the main piston arrives at a position about at the middle of its stroke,and then the valve opens suddenly and with considerable force. It is therefore necessary to have the clearance-space small enough to check the movement of the valve, so that it will not strike the stationary piston 1'6 or the head 19. When the main piston reaches the end of its stroke, the stem 13 is adapted to be moved inward by the valve-gear, and the head 19 will then engage with the valve 23 and force the Same to its seat.

It is not necessary that the means operated by the valve-stem for forcing the valve to its seat should extend through the stationary piston 16, for, as shown in Fig. 4, the stationary piston-head may be made solid and the cylinder 14 and the plunger 17 may be dispensed with altogether. In this modied construction the valve is closed by means of the cross-head 31, the ends of which engage with the outer edge of the cylindrical part 24 of the valve and force the valve 23 to its seat.

The hollow stationary piston is shown of cup'- shaped form and is secured in the opening 5 of the' outer plate 4 by means of a flange at its outer end, although it is evident that other means for securing the stationary piston in position may be used, if desired. In the sides of the Vhollow piston the slots 32 are provided, which act as guides for the cross-head 31 and through which the ends of the cross-head project to engage the outer edge of the valve. The cross-head 31 is secured to the valve-operating stem 13, and when this moves outward the valve 23 is adapted to open by excess of pressure in the main cylinder and at the end of its opening movement the valve cushions on the air between the stationary piston 16 and the valve 23 after the openings 25 have been closed. At the inward stroke of the stem 13 the ends of the cross-head 31 engage the outer edge of the cylindrical part of the valve and force the same to its seat. In other respects the operation is similar to that before described.

Having now fully described my invention, what I claim as new, and desire to secure by Letters Patent, is=- 1. In an air-compressor, the combination of an outlet-valve having a hollow cylindrical extension, a stationary piston within said extension, said valve being adapted to cushion on the air between the stationary piston and the valve, and means actuated by the valvegear for forcing the valve to its seat, said means being free from frictional contact with the inner cylindrical surface of the valve.

2. In an air-compressor, the combination of an outlet-valve having a hollow cylindrical extension and adapted to open automatically by excess of air-pressure in the cylinder, a stationary piston within said cylindrical extension, means for conning air between said stationary pistou and the valve during its opening movement, and mechanism actuated by the valve-gear but out of contact with the inner cylindrical surface of the valve for forcing said valve to its seat.

3. The combination, in an air-compressor, of a cup-shaped outlet-'valve adapted to be opened by excess pressure in the cylinder, a stationary piston within the valve, and means, disconnected from the valve, and out of contact with its inner cylindrical surface, actuated by the valve-gear for forcing said valve to its seat, said valve being adapted to elishion on the air between the stationary piston and the valve.

4. In an air-compressor, the combination with an outlet-valve having a hollow cylindrical extension of a stationary piston located within the said extension, a stem actuated by the valve-gear for forcing the valve to it-s seat, said stem being disconnected from the valve and free from frictional contact with the interior cylindrical surface thereof.

5. In an air-compressor, the combination,of an outlet-valve having a cylindrical extension, a stationary piston located within said IIO cylindrical extension, a stem extending through the stationary piston and actuated by the valve-gear to force said valve to its seat, said stem being disconnected from the valve and free from frictional contact with the inner cylindrical surface thereof.

6. In an air-compressor, the combination of van outletlvalve having a cylindrical extenanoutlet-valve having a hollow cylindrical extension, and adapted to open by excess pressure in the cylinder, a stationary piston within said extension, a stem actuated by the valve-gear, and a head of less area than the interior of the said extension secured to said stem and adapted to be withdrawn into an opening in the stationary piston.

8. In an air-compressor, the combination of an outlet-valve having a hollow cylindrical extension and adapted to open by excess pressure in the cylinder, a stationary piston within said extension serving as a guide for the valve, said piston being provided with a cavity, and a head of less area than the in; terior of the said extension having a guide within said cavity and adapted to be actuated by the valve-gear.

In testimony whereof I have hereunto set my hand. v

JOHN S. LEWIS. Witnessesi MARCUS C. STEERE, CAMERON CAMP. 

